One method to achieve higher recording density using a magnetic head mounted in a hard disk device is to narrow the pitch and/or the bits of the track that are written to the magnetic recording medium (e.g., the hard disk). Referring to FIG. 5A which shows a conventional magnetic write head having a main pole 9, a side gap 8, side shields 7, a trailing gap 18, a trailing shield 14, and a high Bs (saturation magnetic flux density) trailing shield area 19, as a result of narrowing either of the pitch and/or the bits of the track, the area of the main pole 9 on the air-bearing surface (ABS) decreases remarkably, with an accompanying increase in the recording density. The magnetic field generated from the main pole 9 is also reduced in accordance with the narrowing width of the main pole 9 and, in turn, the magnetic recording field required for writing data to the magnetic medium is not able to be produced.
As a countermeasure for this eventuality, as shown in FIG. 5B according to the prior art, a high-frequency magnetic field assisted recording system which performs recording by applying a high-frequency magnetic field to a recording medium to reduce the switching field of the medium and, in this state, applying a recording magnetic field to the medium has been used. One such recording system is a microwave-assisted magnetic recording (MAMR) system. The MAMR head includes a main pole 9, a spin torque oscillator (STO) 10, and a trailing shield 14.
The oscillation properties in a MAMR head are produced through use of the drive of the STO 10 which uses a high current density in order to achieve the necessary assistance. In order to match the position of the magnetic field and the magnetic field-assisted head, the size of the STO 10 is less than the size of the main pole 9, and it is disposed directly above and in contact with the main pole 10.
As shown in FIG. 6A according to the prior art, for a bit density of, for example, 1 Tb/in2, the geometric track width t2 of the main pole 9 is about 45 nm, while the width of the STO 10 correspondent thereto is even smaller, with a geometric track width t1 of about 40 nm. In existing pattern alignment technology, as shown in FIG. 6B according to the prior art, the alignment of a STO 10 at a center of a main pole 9 that is created in an acceptably-high yield process has proved problematic using conventional systems and methods. When misalignment occurs, it affects both the switching field reduction effect on the recording medium and the write width on the recording medium which, in turn, precludes achieving the desired write performance and recording track width. As seen, the high-frequency magnetic field 10e produced by the STO 10 overlaps with the magnetic field 9e produced by the main pole 9 in order for the effects of the STO 10 to enhance writing. Effective writing width t3 is narrower than preferred when misalignment between the main pole 9 and the STO 10 occurs which causes the overlap width to decrease.
Accordingly, it would beneficial to have a magnetic recording system and/or method utilizing MAMR that overcomes these problems.